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Ni Z, Gong Z, Song L, Jia C, Zhang X. Adaptation strategies and functional transitions of microbial community in pyrene-contaminated soils promoted by lead with Pseudomonas veronii and its extracellular polymeric substances. CHEMOSPHERE 2024; 351:141139. [PMID: 38185422 DOI: 10.1016/j.chemosphere.2024.141139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 12/25/2023] [Accepted: 01/04/2024] [Indexed: 01/09/2024]
Abstract
Pyrene was designated as a remediation target in this study, and low contamination of lead (Pb) was set to induce heavy metal stress. Pseudomonas veronii and its extracellular polymeric substances (EPSs) were chosen for biofortification, with the aim of elucidating the structural, metabolic, and functional responses of soil microbial communities. Community analysis of soil microorganisms using high-throughput sequencing showed that the co-addition of P. veronii and EPSs resulted in an increase in relative abundance of phyla associated with pyrene degradation, and formed a symbiotic system dominated by Firmicutes and Proteobacteria, which involved in pyrene metabolism. Co-occurrence network analysis revealed that the module containing P. veronii was the only one exhibiting a positive correlation between bacterial abundance and pyrene removal, indicating the potential of bioaugmentation in enriching functional taxa. Biofortification also enhanced the abundance of functional gene linked to EPS production (biofilm formation-Pseudomonas aeruginosa) and pyrene degradation. Furthermore, 17 potential functional bacteria were screened out using random forest algorithm. Lead contamination further promoted the growth of Proteobacteria, intensified cooperative associations among bacteria, and increased the abundance of bacteria with positive correlation with pyrene degradation. The results offer novel perspectives on alterations in microbial communities resulting from the synergistic impact of heavy metal stress and biofortification.
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Affiliation(s)
- Zijun Ni
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Zongqiang Gong
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
| | - Lei Song
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Chunyun Jia
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
| | - Xiaorong Zhang
- Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China.
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Li L, Hong M, Zhang Y, Paustian K. Soil N 2 O emissions from specialty crop systems: A global estimation and meta-analysis. GLOBAL CHANGE BIOLOGY 2024; 30:e17233. [PMID: 38469991 DOI: 10.1111/gcb.17233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 02/29/2024] [Accepted: 03/01/2024] [Indexed: 03/13/2024]
Abstract
Nitrous oxide (N2 O) exacerbates the greenhouse effect and thus global warming. Agricultural management practices, especially the use of nitrogen (N) fertilizers and irrigation, increase soil N2 O emissions. As a vital sector of global agriculture, specialty crop systems usually require intensive input and management. However, soil N2 O emissions from global specialty crop systems have not been comprehensively evaluated. Here, we synthesized 1137 observations from 114 published studies, conducted a meta-analysis to evaluate the effects of agricultural management and environmental factors on soil N2 O emissions, and estimated global soil N2 O emissions from specialty crop systems. The estimated global N2 O emission from specialty crop soils was 1.5 Tg N2 O-N year-1 , ranging from 0.5 to 4.5 Tg N2 O-N year-1 . Globally, soil N2 O emissions exponentially increased with N fertilizer rates. The effect size of N fertilizer on soil N2 O emissions generally increased with mean annual temperature, mean annual precipitation, and soil organic carbon concentration but decreased with soil pH. Global climate change will further intensify the effect of N fertilizer on soil N2 O emissions. Drip irrigation, fertigation, and reduced tillage can be used as essential strategies to reduce soil N2 O emissions and increase crop yields. Deficit irrigation and non-legume cover crop can reduce soil N2 O emissions but may also lower crop yields. Biochar may have a relatively limited effect on reducing soil N2 O emissions but be effective in increasing crop yields. Our study points toward effective management strategies that have substantial potential for reducing N2 O emissions from global agricultural soils.
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Affiliation(s)
- Lidong Li
- Department of Soil and Crop Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Mu Hong
- Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado, USA
| | - Yao Zhang
- Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado, USA
| | - Keith Paustian
- Department of Soil and Crop Sciences, Colorado State University, Fort Collins, Colorado, USA
- Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado, USA
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Fan Y, Essington M, Zhuang J, Zhang X, Jagadamma S, Schwartz J, Huang J, Bhadha J, Lee J. Recycling silage leachate and biochar for improving nitrate removal by woodchip bioreactor. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 345:118735. [PMID: 37540981 DOI: 10.1016/j.jenvman.2023.118735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 07/22/2023] [Accepted: 07/29/2023] [Indexed: 08/06/2023]
Abstract
Woodchip bioreactor (WBR) is commonly used to remove nitrate from drainage and runoff. However, the efficiency of nitrate removal in WBR is highly variable due to the properties of filling materials. In this study, we investigated the potential of recycling two waste materials, biochar (B) and silage leachate (SL), to enhance nitrate removal by providing a better living habitat and extra available carbon for denitrification. We constructed twelve lab-scale bioreactors with different filling materials (WBR, WBR + B, WBR + SL, WBR + B + SL), hydraulic retention times (HRT: 0.5-24 h), and nitrate concentrations (5.4-33 mg L-1) to test nitrate removal efficiency (NRE) and nitrate removal rate (NRR). Our results showed that the combination of biochar and silage leachate led to the highest NRE and NRR, with improvements of 23% and 48%, respectively, compared to WBR alone. However, the benefits of adding biochar and silage leachate were less apparent at longer HRTs. According to the results of our structural equation modeling (SEM), we have attributed the improved denitrification to several factors. These factors include the decrease in dissolved oxygen, saturated hydraulic conductivity, and pH value, as well as an increase in dissolved organic carbon after the addition of silage leachate. Therefore, our study provides evidence that recycling biochar and silage leachate as an additive to WBR could be a beneficial strategy for enhancing nitrate removal. Overall, this study highlights the potential of a win-win solution to improve the efficiency of nitrate removal in water treatment processes.
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Affiliation(s)
- Yuchuan Fan
- Everglades Research and Education Center, University of Florida, Belle Glade, FL, 33430, USA; Department of Soil, Water, and Ecosystem Sciences, University of Florida, Gainesville, FL, 32611, USA; Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN, 37996, USA
| | - Michael Essington
- Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN, 37996, USA
| | - Jie Zhuang
- Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN, 37996, USA; Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Xi Zhang
- Red River Research Station and School of Plant, Environmental and Soil Sciences, Louisiana State University-Agricultural Center 262 Research Station Drive, Bossier City, LA, 71112, USA
| | - Sindhu Jagadamma
- Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN, 37996, USA
| | - John Schwartz
- Civil and Environmental Engineering Department, University of Tennessee, Knoxville, TN, 37996, USA
| | - Jinsheng Huang
- Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL, 32611, USA
| | - Jehangir Bhadha
- Everglades Research and Education Center, University of Florida, Belle Glade, FL, 33430, USA; Department of Soil, Water, and Ecosystem Sciences, University of Florida, Gainesville, FL, 32611, USA
| | - Jaehoon Lee
- Biosystems Engineering and Soil Science Department, University of Tennessee, Knoxville, TN, 37996, USA.
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Ye H, Tang C, Cao Y, Hou E. Sources and fates of particulate organic matter in inland waters with complex land use patterns. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 877:162568. [PMID: 36889391 DOI: 10.1016/j.scitotenv.2023.162568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 02/26/2023] [Accepted: 02/26/2023] [Indexed: 05/06/2023]
Abstract
Elucidating the sources of particulate organic matter (POM) is the foundation for understanding their fates and the seasonal variation of their movement from the land-to-ocean aquatic continuum (LOAC). The POM from different sources has different reactivity, which determines their fates. However, the key link between the sources and fates of POM, especially in the complex land use watersheds in bays is still unclear. Stable isotopes and contents of organic carbon and nitrogen were applied to reveal them in a complex land use watershed with different gross domestic production (GDP) in a typical Bay, China. Our results showed that the POMs preserved in suspended particulate organic matter (SPM) were weakly controlled by assimilation and decomposition in the main channels. Source apportionments of SPM in the rural area were controlled by soil (46 % ~ 80 %), especially inert soils eroded from land to water due to precipitation. The contribution of phytoplankton resulted from slower water velocity and longer residence time in the rural area. The soil (47 % ~ 78 %) and manure and sewage (10 % ~ 34 %) were the two major contributors to SOMs in the developed and developing urban areas. The manure and sewage were important sources of active POM in the urbanization of different LUI, which showed discrepancies in the three urban areas (10 % ~ 34 %). Due to soil erosion and the most intensive industry supported by GDP, the soil (45 % ~ 47 %) and industrial wastewater (24 % ~ 43 %) were the two major contributors to SOMs in the industrial urban area. This study demonstrated the close relationship between the sources and fates of POM with complex land use patterns, which could reduce uncertainties in future estimates of the LOAC fluxes and secure ecological and environmental barriers in a bay area.
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Affiliation(s)
- Huijun Ye
- School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510006, China; Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510006, China
| | - Changyuan Tang
- School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou 510006, China; School of Geography and Planning, Sun Yat-Sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510006, China
| | - Yingjie Cao
- School of Environmental Science and Engineering, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangzhou 510006, China.
| | - Enqing Hou
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510006, China
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Chen H, Rosinger C, Blagodatsky S, Reichel R, Li B, Kumar A, Rothardt S, Luo J, Brüggemann N, Kage H, Bonkowski M. Straw amendment and nitrification inhibitor controlling N losses and immobilization in a soil cooling-warming experiment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 870:162007. [PMID: 36739009 DOI: 10.1016/j.scitotenv.2023.162007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/25/2023] [Accepted: 01/30/2023] [Indexed: 06/18/2023]
Abstract
It is common practice in agriculture to apply high‑carbon amendments, e.g. straw, or nitrification inhibitors (NI) to reduce soil nitrogen (N) losses. However, little is known on the combined effects of straw and NI and how seasonal soil temperature variations further affect N immobilization. We conducted a 113-day mesocosm experiment with different levels of 15N-fertilizer application (N0: control; N1: 125 kg N ha-1; N2: 250 kg N ha-1) in an agricultural soil, amended with either wheat straw, NI or a combination of both in order to investigate N retention and loss from soil after a cooling-warming phase simulating a seasonal temperature shift, i.e., 30 days cooling phase at 7 °C and 10 days warming phase at 21 °C. Subsequently, soils were planted with barley as phytometers to study 15N-transfer to a following crop. Straw addition significantly reduced soil N-losses due to microbial N immobilization. Although carbon added as straw led to increased N2O emissions at high N fertilization, this was partly counterbalanced by NI. Soil cooling-warming strongly increased ammonification (+77 %), while nitrification was suppressed, and straw-induced microbial N immobilization dominated. N immobilized after straw addition was mineralized at the end of the experiment as indicated by structural equation models. Re-mineralization in N2 was sufficient, but still suboptimal in N0 and N1 at critical times of early barley growth. N-use efficiency of the 15N tracer decreased with fertilization intensity from 50 % in N1 to 35 % in N2, and straw amendment reduced NUE to 25 % at both fertilization rates. Straw amendment was most powerful in reducing N-losses (-41 %), in particular under variable soil temperature conditions, but NI enforced its effects by reducing N2O emission (-40 %) in N2 treatment. Sufficient N-fertilization coupled with straw application is required to adjust the timely re-mineralization of N for subsequent crops.
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Affiliation(s)
- Hao Chen
- University of Cologne, Institute of Zoology, Department of Biology, Germany
| | - Christoph Rosinger
- Institute of Soil Research, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences (BOKU), Peter Jordan Straße 82, 1190 Vienna, Austria; Institute of Agronomy, Department of Crop Sciences, University of Natural Resources and Life Sciences (BOKU), Konrad Lorenz-Straße 24, 3430 Tulln an der Donau, Austria
| | - Sergey Blagodatsky
- University of Cologne, Institute of Zoology, Department of Biology, Germany.
| | - Rüdiger Reichel
- Forschungszentrum Jülich GmbH, Institute of Bio-and Geosciences, Agrosphere (IBG-3), Jülich, Germany
| | - Bo Li
- College of Natural Resources and Environment, South China Agricultural University, Guangzhou, Guangdong 510642, PR China
| | - Amit Kumar
- Institute of Ecology, Leuphana University Lüneburg, Universitätsallee 1, 21335 Lüneburg, Germany; Department of Biology, College of Science, United Arab Emirates University, 15551 Al Ain, UAE
| | - Steffen Rothardt
- Agronomy and Crop Science, Institute of Crop Science and Plant Breeding, Christian-Albrechts-University, Kiel, Germany
| | - Jie Luo
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Nicolas Brüggemann
- Forschungszentrum Jülich GmbH, Institute of Bio-and Geosciences, Agrosphere (IBG-3), Jülich, Germany
| | - Henning Kage
- Agronomy and Crop Science, Institute of Crop Science and Plant Breeding, Christian-Albrechts-University, Kiel, Germany
| | - Michael Bonkowski
- University of Cologne, Institute of Zoology, Department of Biology, Germany
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Nouri A, Lukas S, Singh S, Singh S, Machado S. When do cover crops reduce nitrate leaching? A global meta-analysis. GLOBAL CHANGE BIOLOGY 2022; 28:4736-4749. [PMID: 35583665 PMCID: PMC9328130 DOI: 10.1111/gcb.16269] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 04/13/2022] [Accepted: 05/05/2022] [Indexed: 05/16/2023]
Abstract
The global increases in the surface and groundwater nitrate (NO3 - ) concentrations due to synthetic fertilizer input have emerged as major sustainability threats to terrestrial and aquatic ecosystems. Cover crops can reportedly reduce nitrate leaching from croplands. However, the underlying mechanisms and the effectiveness of cover crops in reducing nitrate leaching across species, soil types, agronomic management, and climates remain elusive. We conducted a global meta-analysis to evaluate the effects of cover crops on nitrate leaching and water drainage. A random-effects analysis was established to investigate seven moderating variables in 41 articles. Results showed that globally, cover crops reduced nitrate leaching by 69% compared with fallow while demonstrating no effect on water drainage. Overall, cover crops from Brassicaceae and Poaceae families showed the greatest effect with 75% and 52% reduction in nitrate leaching, respectively. Cover cropping on Ultisols, Histosols, and Inceptisols resulted in the greatest reduction in nitrate leaching (77%, 78%, and 77%, respectively). Greater efficacy of cover crops at reducing nitrate leaching was evident with increasing soil sand content. In general, cover crops appeared to perform better to reduce nitrate leaching in vegetable systems compared to field crops. Cover cropping on conventional tillage resulted in a 63% reduction in nitrate leaching compared with no-tillage (50%) and reduced tillage (38%) systems. The impact of cover crops on water drainage was nonsignificant which implies that nitrate leaching control by cover crops is unlikely exerted through reducing water drainage. This study brings further insight into the intrinsic factors affecting cover crop efficacy and management practices that enhance cover crop potential in reducing nitrate leaching from agricultural systems.
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Affiliation(s)
- Amin Nouri
- Hermiston Agricultural Research and Extension CenterOregon State UniversityHermistonOregonUSA
| | - Scott Lukas
- Hermiston Agricultural Research and Extension CenterOregon State UniversityHermistonOregonUSA
| | - Shikha Singh
- Hermiston Agricultural Research and Extension CenterOregon State UniversityHermistonOregonUSA
| | - Surendra Singh
- Columbia Basin Agricultural Research CenterOregon State UniversityAdamsOregonUSA
| | - Stephen Machado
- Columbia Basin Agricultural Research CenterOregon State UniversityAdamsOregonUSA
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Duan N, Li L, Liang X, Fine A, Zhuang J, Radosevich M, Schaeffer SM. Variation in Bacterial Community Structure Under Long-Term Fertilization, Tillage, and Cover Cropping in Continuous Cotton Production. Front Microbiol 2022; 13:847005. [PMID: 35444635 PMCID: PMC9015707 DOI: 10.3389/fmicb.2022.847005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 02/15/2022] [Indexed: 11/13/2022] Open
Abstract
Agricultural practices alter the structure and functions of soil microbial community. However, few studies have documented the alterations of bacterial communities in soils under long-term conservation management practices for continuous crop production. In this study, we evaluated soil bacterial diversity using 16S rRNA gene sequencing and soil physical and chemical properties within 12 combinations of inorganic N fertilization, cover cropping, and tillage throughout a cotton production cycle. Soil was collected from field plots of the West Tennessee Agriculture Research and Education Center in Jackson, TN, United States. The site has been under continuous cotton production for 38 years. A total of 38,038 OTUs were detected across 171 soil samples. The dominant bacterial phyla were Proteobacteria, Acidobacteria, Actinobacteria, Verrucomicrobia, and Chloroflexi, accounting for ∼70% of the total bacterial community membership. Conventional tillage increased alpha diversity in soil samples collected in different stages of cotton production. The effects of inorganic N fertilization and conventional tillage on the structure of bacterial communities were significant at all four sampling dates (p < 0.01). However, cover cropping (p < 0.05) and soil moisture content (p < 0.05) only showed significant influence on the bacterial community structure after burn-down of the cover crops and before planting of cotton (May). Nitrate-N appeared to have a significant effect on the structure of bacterial communities after inorganic fertilization and at the peak of cotton growth (p < 0.01). Structural equation modeling revealed that the relative abundances of denitrifying and nitrifying bacteria were higher when conventional tillage and vetch cover crop practices were applied, respectively. Our results indicate that long-term tillage and fertilization are key factors increasing the diversity and restructuring the composition of bacterial communities, whereas cover cropping may have shorter-term effects on soil bacteria community structure. In this study, management practices might positively influence relative abundances of bacterial functional groups associated with N cycling. The bacteria functional groups may build a network for providing N and meet microbial N needs in the long term.
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Affiliation(s)
- Ning Duan
- Department of Biosystems Engineering and Soil Science, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Lidong Li
- Department of Agronomy and Horticulture, University of Nebraska–Lincoln, Lincoln, NE, United States
| | - Xiaolong Liang
- Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO, United States
| | - Aubrey Fine
- Department of Biosystems Engineering and Soil Science, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Jie Zhuang
- Department of Biosystems Engineering and Soil Science, The University of Tennessee, Knoxville, Knoxville, TN, United States
- Center for Environmental Biotechnology, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Mark Radosevich
- Department of Biosystems Engineering and Soil Science, The University of Tennessee, Knoxville, Knoxville, TN, United States
| | - Sean M. Schaeffer
- Department of Biosystems Engineering and Soil Science, The University of Tennessee, Knoxville, Knoxville, TN, United States
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Teng L, Liu H, Chu X, Song X, Shi L. Effect of precipitation change on the photosynthetic performance of Phragmites australis under elevated temperature conditions. PeerJ 2022; 10:e13087. [PMID: 35291483 PMCID: PMC8918233 DOI: 10.7717/peerj.13087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 02/17/2022] [Indexed: 01/12/2023] Open
Abstract
Background As a fundamental metabolism, leaf photosynthesis not only provides necessary energy for plant survival and growth but also plays an important role in global carbon fixation. However, photosynthesis is highly susceptible to environmental stresses and can be significantly influenced by future climate change. Methods In this study, we examined the photosynthetic responses of Phragmites australis (P. australis) to three precipitation treatments (control, decreased 30%, and increased 30%) under two thermal regimes (ambient temperature and +4 °C) in environment-controlled chambers. Results Our results showed that the net CO2 assimilation rate (P n), maximal rate of Rubisco (V cmax), maximal rate of ribulose-bisphosphate (RuBP) regeneration (J max) and chlorophyll (Chl) content were enhanced under increased precipitation condition, but were declined drastically under the condition of water deficit. The increased precipitation had no significant effect on malondialdehyde (MDA) content (p > 0.05), but water deficit drastically enhanced the MDA content by 10.1%. Meanwhile, a high temperature inhibited the positive effects of increased precipitation, aggravated the adverse effects of drought. The combination of high temperature and water deficit had more detrimental effect on P. australis than a single factor. Moreover, non-stomatal limitation caused by precipitation change played a major role in determining carbon assimilation rate. Under ambient temperature, Chl content had close relationship with P n (R2 = 0.86, p < 0.01). Under high temperature, P n was ralated to MDA content (R2 = 0.81, p < 0.01). High temperature disrupted the balance between V cmax and J max (the ratio of J max to V cmax decreased from 1.88 to 1.12) which resulted in a negative effect on the photosynthesis of P. australis. Furthermore, by the analysis of Chl fluorescence, we found that the xanthophyll cycle-mediated thermal dissipation played a major role in PSII photoprotection, resulting in no significant change on actual PSII quantum yield (Φ PSII) under both changing precipitation and high temperature conditions. Conclusions Our results highlight the significant role of precipitation change in regulating the photosynthetic performance of P. australis under elevated temperature conditions, which may exacerbate the drought-induced primary productivity reduction of P. australis under future climate scenarios.
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Affiliation(s)
| | | | | | | | - Lianhui Shi
- Shandong Agricultural University, Taian, China
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A steady-state N balance approach for sustainable smallholder farming. Proc Natl Acad Sci U S A 2021; 118:2106576118. [PMID: 34556575 DOI: 10.1073/pnas.2106576118] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2021] [Indexed: 11/18/2022] Open
Abstract
Hundreds of millions of smallholders in emerging countries substantially overuse nitrogen (N) fertilizers, driving local environmental pollution and global climate change. Despite local demonstration-scale successes, widespread mobilization of smallholders to adopt precise N management practices remains a challenge, largely due to associated high costs and complicated sampling and calculations. Here, we propose a long-term steady-state N balance (SSNB) approach without these complications that is suitable for sustainable smallholder farming. The hypothesis underpinning the concept of SSNB is that an intensively cultivated soil-crop system with excessive N inputs and high N losses can be transformed into a steady-state system with minimal losses while maintaining high yields. Based on SSNB, we estimate the optimized N application range across 3,824 crop counties for the three staple crops in China. We evaluated SSNB first in ca. 18,000 researcher-managed on-farm trials followed by testing in on-farm trials with 13,760 smallholders who applied SSNB-optimized N rates under the guidance of local extension staff. Results showed that SSNB could significantly reduce N fertilizer use by 21 to 28% while maintaining or increasing yields by 6 to 7%, compared to current smallholder practices. The SSNB approach could become an effective tool contributing to the global N sustainability of smallholder agriculture.
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